(1) Field of the Invention
The present invention relates to the technique of recovery of the heaviest hydrocarbons from a gaseous mixture. More particularly, the present invention concerns a process for the recovery of the heaviest hydrocarbons from a gaseous mixture containing in addition, lighter components such as hydrogen, for example for the recovery of GPL (C.sub.3.sup.30 ) from a residual gas of petroleum refinery.
(2) Description of Prior Art
In the known processes for the recovery of GPL, the hydrogen is just about completely removed by a partial condensation of the mixture up to about -80.degree. C.
This technique has many disadvantages:
the obtention of a low temperature of -80.degree. C. leads to the utilisation of a costly two stage refrigerating unit;
the yield of recovery of the GPL is limited as a function of the low temperature selected, for example 97 or 98% for -80.degree. C.;
the heat exchange line constitutes a costly investment;
the benzene compounds and water, even when present at very low concentration, may crystallize in the heat exchange line, leading to pluggings; it is therefore necessary to previously remove these components.
The invention is intended to provide a process which is clearly more economical and which overcomes all these disadvantages.